The present invention relates generally to the field of operator controls for remotely controlled vehicles, and more particularly to a controller designed to be used to control walk-behind, stationary, or ride-on machinery such as pallet trucks, long load transporters, aircraft engine handling devices, scissors lifts, especially omni or multi-directional vehicles or machinery and other industrial machinery.
Walk-behind, remote controlled, and other machines have used various means to convey operator commands to the machine. Some machines have been constructed with either tethered or wireless controls. A tethered control will generally consist of an enclosure to be held by or strapped to an operator. The control enclosure will typically have a “dead man” or enable switch or button, a joy stick or other velocity command input device, mission hardware control input devices such as buttons, toggle switches, one, two, or three axis joy sticks, six-axis force input devices such as a “space ball” or other devices to control embarked machinery and systems, and perhaps an emergency stop button.
Tethered systems are always at risk of the vehicle running over the tether or fouling it on other obstructions. The tether may become entangled in one of the wheels or other moving component and broken, necessitating the machine to be taken out of service.
Tethered systems have the disadvantage that the tethers are relatively delicate and can become damaged by personnel stepping on them, or chafed from being dragged on the ground. Strain relief is another issue, and continual flexing can cause the interconnecting wiring to fatigue and break, potentially resulting in loss of control.
Wireless control systems have also been developed where the operator is equipped with a command input device that is held by the operator while in use. The wireless command input device can also be suspended from a belt or suspenders. Industrial wireless systems can function in most industrial environments, but are not able to function in some military electromagnetic environments, in particular where radars or other high power electromagnetic radiating devices are in use. Wireless systems also emit radio frequency (RF) energy that can interfere with weapons and communication systems in a military environment.
Both tethered and wireless systems have the disadvantage of not conveying the machine's motion directly to the operator via tactile feedback. This is most detrimental when making small, precise motions in constricted environments where an error could damage delicate equipment or injure nearby personnel. An operator that has tactile feel for the machine's motion will be less likely to cause damage in such situations.
Machines controlled via tethered or wireless links can be turned in a direction wherein the front of the machine differs in orientation from the face of the operator, and in such an orientation the operator may become confused and inadvertently command the machine in a direction different from that desired, causing frustration or accidents. This refers, more specifically, to the X and Y axis of the operating station remaining the same as the X and Y axis of the vehicle. In emergency situations this potential for operator confusion or disorientation relative to the front of the machine and hence the direction of travel can be particularly dangerous, since an operator's initial instinctive reaction may be different than that needed to avoid a collision or bystander.
Many industrial and military machines have been equipped with a rigid operator interface. In some cases, as in a commercial powered pallet handler device, the operator interface may take the form of a “T” shaped handle with finger operated paddle controls. The paddle controls may be used to convey velocity commands and or lift and tilt or other commands as appropriate.
Sometimes such operator interfaces are arranged to rotate with the steered wheels, and in some cases, the operator's physical input is used as the steering actuation force. For example, the US Navy MHU191 weapons handler dolly is equipped with an extendable handle that is linked to the front wheels. An operator will rotate the handle about the front of the vehicle to the desired direction to turn and then either push or pull on the handle or other part of the payload or dolly to move it in that direction. Centering the MHU191 dolly handle will cause the MHU191 dolly to move in a straight path when pushed. In another example, a electrically powered pallet jack can have a “T” shaped handle that is connected to powered wheels which are further arranged to support one end of the machine. In order to change the machine's direction of travel, the operator manually rotates the “T” handle about the powered wheels, thereby orienting them into the desired direction.
The aforementioned arrangements have the disadvantage that the operator's juxtaposition to the machine is fixed. That is, the operator must be located centrally behind the machine while traveling a straight path, or to the side of the machine facing the inside of the turn while traveling on a curved path. The operator is not able to, for instance, view the side of the machine facing the outside of a turn, or to walk from a vantage point far to one side of the machine while traveling in a straight path.
Therefore, there exists a need for an operator interface that provides tactile feedback to the operator. There also exists a need for a walk behind machine operator interface that permits the operator to walk from different vantage points while the machine is in motion and under control. There also is a need for an operator interface that provides tactile feedback and that can be relocated all while maintaining a constant rotational geometry about the vertical axis.